1. Field of the Invention
This invention relates to a device for transmitting motion by a cable located within a flexible conduit and extending along a curved path. More particularly, this invention pertains to a device for automatically adjusting the position of one end of a cable with respect to a reference position at the opposite end of the cable.
2. Description of the Prior Art
Cable assemblies that transmit motion from one moveable component to another generally include a device located at each end of a conduit for attaching a conduit to a supporting structure. A cable, located within the conduit, extends from each end of the conduit. The purpose of the cable is to transmit motion of a device, to which one end of the cable is attached, to another device at the opposite end of the cable. Generally the cable assembly including the conduit is in the form of a loop that extends between the two attachments at the ends of the cable. The diameter of the conduit is substantially larger than the diameter of the cable; therefore, the cable can move laterally within the conduit until it contacts the restraining inner surface of the conduit. This produces a condition called backlash or lost motion, i.e., a difference between the displacement of the reference end of the cable and the displacement produced at the opposite end of the cable.
Usually the cable transmits motion both in tension and compression between the reference position and the opposite end of the cable. Frequently in assemblies of this type, displacement of the reference position must be closely related to the corresponding displacement at the opposite end of the cable so that the reference motion produces a corresponding movement, within an acceptable tolerance, at the opposite end of the cable. When the critical condition for producing this corresponding displacement causes compression in the cable located within the conduit, some means external to the cable itself must be applied to bias backlash and to produce a resulting displacement that is within a consistently close tolerance of the displacement of the reference end of the cable.
U.S. Pat. No. 4,669,330 describes a cable length adjuster that includes a compression spring located along the cable length between a housing and a device that locks the cable with respect to the housing. A pivoting latch aligns the locking device with teeth formed on a surface of the housing, thereby forcing the teeth into engaging contact with teeth formed on the housing. The pivoting member holds the cable in this locked position but the compression spring is ineffective toward locating an attachment at one end of the cable with respect to a desired position for that attachment.